While this had already been done using rodent stem cells, this is the first time that these types of cells -- called primordial germ cells -- have been produced efficiently using human stem cells, according to the team at the University of Cambridge in England.

"The creation of primordial germ cells is one of the earliest events during early mammalian development," study first author Naoko Irie said in a university news release.

"It's a stage we've managed to recreate using stem cells from mice and rats, but until now few researchers have done this systematically using human stem cells. It has highlighted important differences between embryo development in humans and rodents that may mean findings in mice and rats may not be directly extrapolated to humans."